At a low part-load and idling it is difficult to achieve a good fuel economy and acceptable emission rates of a vehicle machinery. When said machinery comprises a gas turbine, the work for driving the compressor and auxiliary apparatuses is very heavy during said operation conditions.
For normal driving there should be a certain power available, but in order to counteract above mentioned disadvantages at part load and idle running, it is according to the present invention proposed, that the turbine, including its combustor, is so formed that a low r.p.m. it is not able alone to drive the main rotor, i.e. the rotor comprising the compressor, as well as the auxiliary apparatuses.